We follow the twist expansion in the TMD factorization formalism [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, [8]},
where the twist-2 contribution comes from \(\mathcal {W}^{+i;+j}\) ,
the twist-3 contribution comes from \(\mathcal {W}^{+i;+-}\)  and \(\mathcal {W}^{ij;l+}\) ,
and \(\mathcal {W}^{+-;+-}\)  contributes at twist-4.
